JPS60256065A - Accelerometer of running object - Google Patents

Abstract

PURPOSE:To detect the acceleration in the advance direction of a car body from which the effect of acceleration in the lateral direction, which is caused by the acceleration of gravity due to inclination of the car body and the revolution of the car body, is perfectly removed, by using four accelerometers. CONSTITUTION:Data a, b, c and d of respective accelerometers a, b, c, d are added by adders 1, 3 and subtracted by subtractors 2, 4 and further divided by acceleration of gravity to calculate measured quantities A, B, C, D. Because a speed is V=0 when a car body starts, the left and right inclination angle phi is immediately calculated from the measured quantity C and, if this inclination angle phi is put in the measured quantity B to perform processing, alpha/G (acceleration in advance direction/acceleration of gravity) is calculated. If this value is integrated with respect to a time by an integrator 5, a speed V is calculated.

Description

[Detailed Description of the Invention] The present invention relates to a moving object such as a car (hereinafter simply referred to as a vehicle body).
This is related to the velocity in the direction of travel.

Acceleration indicator is used to calculate speed from the acceleration of a moving object.Currently, most vehicle speedometers take their signals from the rotational speed of the axle. However, it may be difficult to measure the actual ground speed if the tire diameter changes due to variations in tire air pressure and loaded weight, or the tire and the ground may slip.

Therefore, attempts have been made to measure the acceleration of the vehicle body in the direction of travel and integrate this over time to calculate the speed. However, this includes the effects of gravitational acceleration due to the vehicle's forward direction and lateral inclination, as well as the effects of lateral acceleration when the vehicle is turning, making it impossible to accurately measure the entire acceleration in the vehicle's forward direction. .

The present invention has been made to eliminate the above-mentioned drawbacks and to accurately measure the entire acceleration in the direction of travel of the vehicle.The present invention is characterized by the fact that the acceleration sensing direction of the two accelerometers is determined by the vertical line of the vehicle and the direction of travel of the vehicle. The other two accelerometers are installed at an angle of 45 degrees with respect to the vertical line of the vehicle body, that is, the acceleration sensing directions of both speedometers are at right angles to each other. It has been installed so that the direction is perpendicular to the plane determined by the car body vertical line and the car body traveling direction.

The drawings will be explained in detail below. FIGS. 1 and 2 show the arrangement of accelerometers and their acceleration sensing directions, illustrating the measurement principle of the present invention.

b, c and d represent the direction in which the ZJ direction of the accelerometers senses all positive acceleration. GLf'i is a horizontal plane, Ov is a vertical line with respect to the horizontal plane, and G is the acceleration of gravity.

Figure 1 shows two accelerometers a placed in the direction of travel of the vehicle.
This is a diagram showing the relative arrangement of item b viewed from the side, where OM represents the vertical direction of the vehicle body. θ represents the inclination of the vehicle body in the traveling direction with respect to the vertical line Ov.

The positive acceleration sensing directions 2 of the accelerometers a and b are each inclined at 45 degrees with respect to the vertical line oM of the vehicle body within a plane determined by the vertical MOM of the vehicle body and the direction of travel of the vehicle body. That is, the sensing directions of accelerometers a and b are tilted at 90 degrees to each other.

Figure 2 shows two accelerometers C installed on both sides of the vehicle body.
, a, as viewed from the rear of the vehicle body, and are installed on the left and right sides of the vehicle body width.

The positive acceleration sensing direction is perpendicular to the plane defined by the vertical line OM of the vehicle body and the direction of travel of the vehicle body, and is in the same direction. H is c
, d is the mounting interval between the two accelerometers, and ψ represents the inclination in the direction perpendicular to the traveling direction of the vehicle body with respect to the vertical line Ov.

Now, let us assume that the vehicle is traveling at an acceleration of α in the direction of travel, simultaneously turns to the left with respect to the direction of travel, and is receiving an acceleration of β at the center of both accelerometers c and d.

Acceleration Ml detected by accelerometers a and b aα・1, bα respectively
Then, the equation (1) follows.

Here, when aα+bα and aα−1bα are included, equation (2) is obtained.

Rearranging equation (2), we get equation (3).

Here, A, Bi are newly defined as in equations (4) and (5).

The acceleration detected by accelerometers c and d in Figure 2 is C
Let β, dβ be, and if the car body is turning to the left in the direction of travel with a turning radius R1 and a speed V, σβ and dβ are expressed by formula (6)%. However, β is the acceleration generated by the car turning. Total C
, a is the acceleration at the center of the vehicle, and Δβ is the acceleration due to inside the vehicle.
This is the change in .

From equation (6), equation (7) is obtained.

Here, O and D are newly defined as in equations (8) and (9), and therefore equations (8) and (9) become as shown in equations (l(), 61).

C= −7#@sinψ ・・・・・・・・・・・・
...... (10Δβ 1) = - Jlij A, B, C and D that can be measured.

FIG. S shows an embodiment of the subtraction means of the present invention, in which / and 3 are adders, and Z and Z are subtractors. is an integrator for time, and the other symbols are as described above.

In Fig. 5, accelerometers a and b.

The respective data of C and d aα, bα, Cβ and dβ are added by full adders / and 3, subtracted by subtractors C and G, and further divided by the acceleration of gravity to calculate A, B, C and DQ. When the car body starts, the speed v = Q, so ψ is immediately calculated from C, and if you put this in B and process it, θ will be reduced.If you add ψ and θ to AK and process it, α/G will be calculated. It will be done. This is an integrator! If you integrate over time, you will get the velocity V. The above routes are shown by solid lines in Figure 3.
-If the variable speed V is equalized, ψ is equalized by putting it into D and processing it. This route is shown as a dotted line. Once ψ is equal to ψ, the speeds V can be determined one after another using the method described above.

Note that the acceleration sensing directions 2 of accelerometers a and b are tilted at 45 degrees to the vertical line OM of the vehicle body, as shown in FIG. It is not necessary to limit the acceleration sensing direction Z of the image speedometers a and b to be at right angles.

As described above in detail with reference to the drawings, according to the present invention, by using four accelerometers, the effects of gravitational acceleration due to the tilt of the vehicle body and lateral acceleration due to the turning of the vehicle body are completely eliminated. Since the acceleration in the traveling direction of the vehicle body is detected, this method is much more effective than other detection methods based on the acceleration liver method.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the arrangement of accelerometers and their acceleration sensing directions, illustrating the measurement principle of the present invention, and FIG. 5 is a diagram illustrating an embodiment of the means for realizing the present invention. a, b, c and d...accelerometer, Z...acceleration sensing direction, GL...horizontal plane, Ov...vertical line, O
M...Vertical line of the vehicle body, G...Gravity acceleration, α
...Acceleration in the direction of travel, β・Acceleration in the direction perpendicular to the direction of travel, σ, ψ...Inclination angle of the vehicle body, H...c
, d accelerometer spacing, / and 3...adder, λ and g...
...Subtractor! ...Integrator. Patent applicant: International Technology Development Co., Ltd.

Claims (2)

[Claims] (1) The two accelerometers are arranged so that the acceleration sensing directions are perpendicular to each other within the plane defined by the vertical line of the moving object and the direction of movement of the moving object, and the other two accelerometers are placed in the direction of the moving object. They are placed on both sides, and the acceleration sensing direction is perpendicular to the plane determined by the vertical line of the strike object and the traveling direction of the moving object! : An accelerometer for moving objects characterized by: (2) There is an in-plane pressure whose acceleration sensing direction is determined by the vertical line of the running object and the traveling direction of the running object, and the acceleration sensing directions of the two accelerometers arranged at right angles to each other are 45 degrees with respect to the running object perpendicular +l1lilK. An accelerometer for a running object according to claim 1, characterized in that it is tilted.